Steroid hormones, in conjunction with nuclear receptors, have pronounced effects on cell differentiation and gene action. The chicken oviduct is a particularly valuable model system for studying the control of gene expression because estrogen, progesterone and testosterone are involved in the regulation of the synthesis of several abundant egg white protein mRNAs, including those for ovalbumin and conalbumin, which can be studied both functionally and chemically. We propose to continue our work on this system by: (a) examining the processes involved in the acquisition of hormonal responsiveness during oviduct embryogenesis; (b) exploring the biochemical mechanisms responsible for tubular gland cell death during hormonal withdrawal; (c) measuring the rates of transcription of ovalbumin and conalbumin mRNA during hormonal induction and comparing any changes in these rates with changes in the sensitivity of these genes to DNase; (d) fractionating chromatin into transcriptionally active regions and then examining the non-histone proteins (including steroid receptors), histones, and RNA species for evidence of enrichment in these fractions and hormonal dependency; (e) comparing the regulation of conalbumin and transferrin mRNA transcription and translation in the oviduct and liver, respectively, since there is evidence that these proteins may be products of the same gene; and (f) investigating the mechanism of protein secretion in the oviduct and the liver. We anticipate that these studies will provide a broader understanding of steroid hormone action and better insights into the mechanisms of cell determination and cell differentiation.